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Hi everyone!Is there anything wrong with using a conical horn for the midrange, say a range from 300Hz to 1.6KHz?
People are always reccomending Tractrix or Hyperbolic for the midrange, but never conical. A couple of months back I built two Tractrix horns for some Alpha 6 drivers I've got, they perform great, but I just found today in a Hornresp simulation that if I built a conical horn then the HF response would be even higher which is good.
Are conical horns the straight sided horn? Is the Unity horn a conical horn?
If its a straight sided conical horn, it isn't a CD horn is it, I could make wider coverage angle in the horizontal than the vertical planes if I wanted?
So whats the pro's/con's of a conical midrange over a tractrix midrange horn?
Follow Ups:
I thought you might like to see some measurements of a conical horn.
Please see graph under ”RCA-Fan”Here is a conical horn about 60 deg, 12” long by 15” in dia.
Measured 1w/1m with a BMS 1” driver. You can see the directivity is very good, and the curve is smooth.
A Tractrix horn is shown as well with a B+C 2" driver. Note the increased bandwidth.The things I like about Conical horns is that they are the least disruptive to the wavefront, resulting in a more natural sound if you talk through them.
If you consider a tube ( organ pipe) you get one really loud note with a lot of resonances.
From a tube to a conical horn, the conical horn produces less resonances. They track the wavefront more precisely.The bad points are- the low frequency out put is poor considering horns of the same cubic volume.
Sometimes wide directivity can “ de- focus” the sound image in a stereo situation.Tractrix and exponential horns are tend to equalize up the top end as they have less directivity. Conical horns always have dwindling high frequency response.
Finally Multi-cells are a series of small exponential horns; working in unison relative to directivity can give a very “big” sound image.
I personally favor the conical horn as the driver at higher frequencies has enough to deal with, and adding wavefront manipulation gives that “horn-like” sound.
You can see the graphs under RCA-Fan in the Gallery.
Bill
Hey BillSome interesting measurements there! It confirms what I thought, the conicals seem very good off-axis too their on-axis response. Thanks for those graphs. I've made the decision to go ahead and try out some conical horns with a few compression rings and do lots of measurement comparisons between 'em. From what I've gathered about the conicals, they seem more advantagous to the tractrix horn flare for my application.
Hi All,At the last Oswalds Mill event a couple of weeks ago, Bill Woods, speaker designer and engineer at Yorkville Sound, brought down a prototype aluminum casting of a round conical horn, 700hz flare. This was a very heavy casting, non resonant, and he had a throat adapter for the RCA 1428B. We compared this horn to my big RCA 300hz 18cell horns. The result astonished me. The clarity in the upper midrange was breathtaking. I was immediately convinced (and put myself down on the waiting list for a pair.) I plan on adding them to the big multicells to get the best of both worlds- i.e. the dispersion and lower midrange the multicells do so well, along with the clarity and openness of the conicals in the upper midrange. It amazes me that while everyone has been running after the tractrix horns the last few years, conicals have been largely overlooked.
snip>
"conicals have been largely overlooked."Hi
The horn lore was that they sounded bad, go figure.
I have found them to have some "good properties" as well.
I finally got to meet Bill W and Todd M.(and Bill M. from this list)up in Canada a couple months ago, really nice guys and Bill is quite the speaker historian.
Cheers,
Tom you left us hanging why don't you expand on your comments. Good vs the Bad."I have found them to have good properties as well (as bad ones??)
like sizing, what driver to use, throut design.......cheers.
See my links page which contains a number of useful links to sites about horn design, other DIY projects, etc.http://www.geocities.com/adrian_mack/links.html
Hello!
I've read many posts of people that have stated that the hornresp highcutoff response extends at least an octave above, so I'm not sure if you should trust what it says.
But I'd give it a try anyway, if you got some spare MDF :) I can't really comment on the performance since I've never compared the horns in reality.Good luck!
Hey Mattias,Yep, I've heard that too, I've forgotten why though, I've got it in one of my emails or something.
Those F3 points for my tractrix horn is what I measured though. I didn't find that there was really any more HF extension than what Hornresp predicted on my horn, so I'm not sure that I'd wanna trust all simulations to go higher than what it predicts. It would be different for each case though I guess.
Hi Adrian,
Whoa boy, good question, even if you have tapped the hornets' nest a bit.In the late 1940s and early 1950s, an engineer at RCA built and extensively tested many conical horns. As he has related to me, he loved their dispersion characteristics, which basically followed the angles of the straight sided walls. RCA never produced any conical horns for sale, though, and the reason? They had to be significantly larger for a given low frequency cutoff. Size is such an important consideration in almost any commercial horn design.
Neil borrowed one of my conical midrange horns recently, and took it to Dr. Edgar's lab for LMS measurements. The results look fairly bad on paper. Compared to one of Dr. Edgar's tractrix midrange horns, the conical is much larger physically, and rolls off sooner on both the low and high end than the tractrix in on-axis response measurements. My take on it is that the lows roll off sooner due to the conical's rapid throat flare and consequent lack of low frequency loading. The highs appear rolled off due to the conical's wider dispersion of highs, and lack of on-axis beaming that the tractrix displays. Case closed? Well, not quite yet.
If the proof of the pudding is in the eating, so it goes with horns. The conical should have lower distortion, due to the lack of throat constriction inherent in a curved flare horn. The highs will look less impressive in an on-axis measurement, as they are dispersed more widely. I built the conical mid horns I am still listening to a year or so ago, and have been very pleased with them. They feature great openness and clarity of sound compared to the 300Hz. RCA and Altec multicellular exponential flare horns I had used previously. They are admittedly huge: 24" by 28" at the mouth, 36" long. In their favor, they are easy to build, being made from chunks of flat plywood. I made an on axis LMS response measurement, and was surprised at the results I got: they are within + or - 4dB from 100Hz to 8kHz. with the RCA MI-1428B drivers I am using. Neil's results using a JBL 2482 driver were much more rolled off in both frequency extremes, which I attribute primarily to driver characteristics.
So, we have a classic audio problem: objective measurements vs. subjective observations. I think that conical flare midrange horns have a lot to offer in sheer naturalness of sound, although admittedly they don't look as good on paper as more conventional solutions... sort of like the SE DHT vs, SS amp debate. I can attest that Dr. Edgar's tractrix mid horns sound extremely good, and image like crazy, so there is no clear winner here... but I am going to hang onto my conical mid horns for now.
Hey Steve,I love the dispersion of the conicals too, the polar response should be much better at the top end of its range compared to a hyperbolic or other curved-sided horn.
It seems to me that the conical horn can go higher than a tractrix even on-axis where the polar pattern isn't lost. I guess I'll find out properly once I build one. I am going to build a conical horn thats got the same length, throat area, and mouth area of my tractrix horn, except it'll be conical design. Hornresp predicts the conical should go higher. Those F3 points on my tractrix horn I listed in my last post was the measured response using Speakerworkshop, so I'll take measurements of the conical too once its built and compare it to my tractrix horn being the same size.
A feature of conical horns is that they all give a peak at cutoff, although the peak can be made so its not really a peak, but there will still be a small dip after it if the peak is not very pronounced.
Have you done any polar plots of your horn? Do they seem to have the same power response off-axis as they do on-axis? (within the dispersion of the wall angles), or does response start to go bad off-axis? Was your conical horn designed to give more dispersion in a particular plane or was it a CD horn design so the same dispersion in both?
Do you know how to actually measure the angle that the wall makes, so that you know what dispersion angle the horn will distribute sound too?
Hi,
I've been using a conical midrange horn for a while now (besides unity horns). It's the big MDF horn, second from the right. This is with a compression driver, but it should work fine for cones as well. Covers 400hz-3khz in my setup.
Hey John,Thats pretty cool, looks like you've got quite a few conical sections on it too.
I've got some spare 12mm MDF left over here from last time, I think I'll play around with some conicals just for fun cuz they look so easy to build.
How's your unity clone going? Have you done any more tweaks on 'em?
I changed the midrange holes on my unity a few months ago to get really good midrange response, but it adversely effected the tweeter (as expected). It did confirm my software model works for predicting performance though, so now I just need to find a different driver that is actually appropriate for this app.
Hi John,How smooth does the frequency response measure, and how does it vary both on and off-axis?
I would love to see a graph, as a conical horn I measured recently measured peaky on axis.
Best,
Neil
Hi Neil,
The response is pretty smooth - it seems to depend on the driver, mostly. I havne't measured off axis with this one. In room, it is pretty much the same everywhere I would want to sit, as the angle between side walls is 40 degrees. I have a phenolic diaphragm 375 on - it's actually a Dukane driver made by JBL.
Hey-Hey!!!,
I was just part of such a discussion at a recent tube tasting adventure in New Tripoli. Turns out that anything other than conical colors the sound by working better at certain frequencies. The conical is not quite as eficient as a properly curve sided horn, but the conical will( insert sweeping generalization here ) be flatter. 'twas an educational experinece. The RCA engineers were an experience not to be missed either, as was their work.
regards,
Douglas
Hey DouglasInteresting, I wonder why I've heard so much more talk about Tractrix then in the midrange?! *&@
Those are what I built a few months back. The F3 points are about 450Hz and ~1.1- 1.2KHz and flat response between those points. A conical horn using the same length/throat/mouth sizes simulates in hornresp response with upper cutoff like 1.8KHz! pretty big difference between the conical and tractrix expansions.
Perhaps I'll build a conical horn too. I imagine it would be heaps easier too because they are all straight/flat walls. Do you know any software which can work the numbers that I need to cut the wood size too? Hornresp only does it for round horns :-(
Hi Adrian,Horns look good. Was the 1k2Hz upper point measured or simulated? Should be able to get much higher with Alpha 6. Don't entirely rely on Hornresp's high frequency simulation. If you cut a few inches from the throat end of your horn so that the throat area can see most of the cone itself, you will get extended top end due to lack of path cancellation, despite the dismal result Hornresp will tell you for this - I have just completed some Beta 8 horns that go to 3khz nicely.
HeyThose F3 points were the measured results. I just couldn't get it to go any higher than that, I tried gapping the driver too like that which is described in the Edgar Midrange Horn article, but it didn't do to much.
The conical that I simulated in hornresp for an Alpha 6 predicts higher HF extension than both the simulated and measured response of the tractrix horns I built, so I must be able to get higher with that!
The Beta 8 horn sounds cool, have you got any pictures of 'em? What sort of horn are they?
Hi Douglas,Did you hve the opportunity to listen to any conical horns? If so, which ones and with what drivers?
It was a custom one-of, brought to the Oswald's Mill event. 700 Hz c/o I think. RCA field coil driver. 'mazing!!!!
regards,
Douglas
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